"I see an exciting adventure in your future, a new sexual experience that forever changes you," she said, tracing the sole of my foot with one soft fingertip. Her husband grinned at me from the bed. I sat half-naked in the overstuffed armchair and trembled with nerves.

This is not how I'd imagined my first — or any — threesome. I'm not bisexual, and I can count the number of times I've been physically attracted to a woman on one hand, with two fingers left over.

Yet here I was in a cute little southern California inn with a couple who have been married for 25 years, playing an adults-only computer game that would have us girls riding double before dinnertime.

Let's Play a Game

It all started when I learned about Onyx, a computer game that takes two to six players on a journey of sexual exploration. A sort of Monopoly-meets-spin-the-bottle-in-a-dungeon, Onyx makes the old-fashioned lovers' card games look like solitaire.

I wanted to try it out, which meant I needed some volunteers. Which I jokingly mentioned at a dinner party. At which point I jokingly accepted my friends' offer.

Only the next day, when they called to schedule the day and time, did I realize they were serious.

I mean, a threesome with another girl? That had never even occurred to me. My group sex fantasies always involved two to six men. The thought of touching a girl down there gave me a serious case of the willies. It still does.

On the other hand, I am known in some small circles as a person willing to try sexual adventures and report back. I couldn't chicken out now over a simple matter of biology.

But as it turns out, Onyx takes that into consideration. Onyx won't assign same-sex actions to players who tell it they are straight, nor will it assign opposite-sex actions to players who define themselves as gay. You can also earn "opt out" cards that let you decline any particular assignment during the game.

Given that the game contains up to 600 action cards, it's not like this lets anyone off the hook.

We giggled our way through the brief pre-game inventory, telling Onyx that we had a vibrator, a dildo, a blindfold, a glass of water in the room — but not a carrot, though I'd love to know what it would have us do with one — and then it was time to roll the dice.

The game board includes several virtual properties you can buy as you land on them, ranging from a massage parlor to an adult toy store to a strip club. When another player lands on your property, she has a choice: pay you rent in cash, or work it off.

Naturally, everyone chooses to work it off.